Help me pick some new or used speaker cables

There are some great options for speaker cables mentioned - I'd also consider Nordost. I've been very impressed with them as with Transparent.  

I've been very pleased splitting my cables - Shunyata for power and Kimber for speakers/interconnects.  

Some great advice thus far. I’d add that buy used because if you don’t achieve what you seek, you can sell them for what you paid. If you buy new, support your local dealer and try them in your system to know 1st hand if it’s the right combo.
 

The cables I’ve liked the best are OCC wire to start with. Ocellia are sublime, and should put you in the right place. If by chance you’re running Sylvania 6SN7 in the MW LS100, get them out in favour of a different tube like some 40, or 50’s RCA. (I had a LS100)

I have tried most of the "high end" name brands and once I found Silversmith Audio Fidelums.....game over.  Well with in your price point new.  ONLY cable I ever purchased that sounded great right out of the box and simply got better with hours.

Better speaker cables, yes!

I may have missed reference(s) to room acoustics on this thread, but certainly worth looking into (if you haven’t already).

Congrats on thinking outside the box with the T-7 mods. Typically "mods" will calm down certain ranges due to incorporating better materials, connection/termination methods, attention to sympahtic resonances, etc. If all else fails you might consider having a conversation with your "modder" about this. I’ve found that bumping up the tweeter crossover point ever so slightly can remove a little hardness.

Hi rkfaberdds...thanks for your question,

My early foray into great audio was a pair of Chapman T-4s, 2 way sealed 45lb monitors that served in several rooms for a couple of decades.  They sit happily with fresh surrounds in a closet upstairs, awaiting new skirts.  Pairing your Chapman 7s with Rogue = music.  Nice going!  

I also am onboard with Cardas. To keep away from black market concerns, I elect to use The Cable Company.   My solution was buying a used pair of Cardas Clear Sky X4 loudspeaker cables which are internally designed for bi-wiring, assuming your 7's are bi-wirable.  I returned the pair to Cardas, having them upgrade only the loudspeaker ends to bi-wired, 4 inputs per side, leaving the outputs as is from the amplifier, 2 outputs per side.  I ALSO paid to upgrade all 12 terminations to compression die forging:

Cardas Compression Die Forging – Audio Advisor (youtube.com) 

I suspect my "flavors" in audio align nicely with George Cardas.  Given your choices, ours probably do as well.  Onwards!

More Peace, Pin           (bold print for old eyes)

...